Dielectric response and complex impedance spectroscopy studies in pulsed laser ablated (Ba, Sr)TiO₃ thin films

Abstract

The dielectric response of pulsed laser ablated barium strontium titanate (Ba, Sr)TiO₃ thin films was studied as a function of frequency, time and ambient temperature. Both time and frequency responses followed the "universal power law" pertaining to the universal dielectric response model theorized by Jonscher. Theoretical fits were used to compare the experimental results and determine the temperature dependence of the theoretical parameters such as n(T) and a(T) used in the universal model. Complex impedance spectroscopy was used to investigate the grain, grain boundary, and electrode/film interface responses. The complex spectroscopic plots revealed the major response originated from the bulk grains while in the case of polycrystalline samples the grain boundary contributed significantly. Arrhenius plot of the bulk resistance calculated from complex impedance diagrams showed a significant difference in the activation energy ranging from 1.17 to 1.23 eV for samples grown at different substrate temperatures.